Plastic container and lid



July 26, 1966 A. 1.. M CONNELL ET AL 3,262,602

PLASTIC CONTAINER AND LID Filed June 17, 1964 m 0 T N E V m ALBERT L.McCONNEL BY ORDON E w? gram United States Patent 3,262,602 PLASTICCONTAINER AND LID Albert L. McConnell, Chester, and Gordon E. Wade, GlenRiddle, Pa., assignors to Scott Paper Company, Philadelphia, Pa., acorporation of Pennsylvania Filed June 17, 1964, Ser. No. 375,828 6Claims. (Cl. 220-60) This invention relates to thin wall, disposableplastic containers of the type in which foodstuffs, such as cottagecheese and ice cream, are packaged. Containersof this type are generallypressure formed in cavity molds from thin plastic sheet material, withthe resulting container being a unitary structure having theconfiguration of the surface of the cavity in which it is formed. Lidsfor such containers are also generally pressure formed from sheetplastic material in a manner similar to that by which the containers areformed.

It is essential from the standpoint of product cleanliness and also toprevent product spillage that the lid form a tight, fluid proof sealwith the container to which it is afiixed. Moreover, the lid must bepositively and mechanically locked to the container to precludeaccidental dislodgement of the lid during transportation and handling ofthe filled container. To achieve these ends it has been the practice toform a groove in the side wall of the container near its open end forreceiving a sealing bead which is formed in the lid and is adapted tosnap into and become mechanically locked in the container groove.

It has been observed that when lids of this character are rapidlyapplied to their containers, under conditions such as those encounteredwhen using automatic filling and lid placing equipment, a substantialquantity of air may be trapped inside the container when the lid isfully seated. This is due to the inherent interference, i.e. overlap,between the lid sealing bead and the mouth of the container. In someinstances the quantity of air involved is such that when the lid isfully in place the air exerts sufiicient forces on the lid to cause thelid to blow oif, either immediately after the lid is in place orsubsequently when the container is subjected to normal handlingactivities.

It is the principal object of this invention to provide a thin wallplastic container to which a flexible snap-in lid can be applied withouttrapping an excessive quantity of air in the container.

The invention contemplates a container in which an outwardly taperingregion of the container wall immediately above the sealing groove in thewall is provided with venting means which permit air to escape frombeneath a lid being applied to the container during that portion of thelid movement in which the lid sealing head is in contact with thesloping region of the container wall.

It is a further object of the invention to provide the above-mentionedventing means with a minimum of modification of the cavity of the moldin which the container is formed. This objective is achieved through thediscovery that entirely adequate venting can be achieved by providingspaced, otfset sections in the tapering region of the container wall,with the offset being no greater than the thickness of the containerwall.

Other objects, advantages and features of the invention will be apparentfrom the following detailed description of the invention in whichreference is made to the accompanying drawing wherein:

FIG. 1 is a perspective view of a container-lid combinationincorporating this invention and from which portions of the structurehave been broken away to show the 'wall structure of the container andthe lid;

FIG. 2 is an enlarged vertical section-a1 view of the 3,262,602 PatentedJuly 26, 1966 ice upper portion of the container wall and a portion ofthe lid being applied to the container;

FIG. 3 is a view similar to FIG. 2, but illustrating the container withthe lid in sealing relationship therewith; and,

FIG. 4 is a fragmentary sectional view through the venting means of thecontainer taken' generally as indicated by the line IV-IV in FIG. 2.

Referring particularly to FIG. 1, the container of this invention isidentified generally by reference numeral 11 and the lid therefor byreference numeral 12. Container 11 is an integral structure formed of asingle sheet of plastic material and which possesses a tapering sidewall 13 and a bottom wall 14. Such containers are generlly vacuum formedfrom a single sheet of plastic material, such as polystyrene, whichafter being softened by the application of heat is drawn or forced intoa female mold by means of vacuum, pressure or a combination of vacuumand pressure. The mold used for this purpose has an interior surfacehaving a configuration closely mate-hing the desired final configurationof the container. In other words, any grooves or rings desired in thewall 13 of the container 11 are produced by corresponding grooves orrings in the side wall of the mold. With certain limitations, thecontainer 11 may have any desired configuration.

If desired, containerll may be provided with a reinforced rim 15 at itsmouth by rolling over a portion of the material of the side wall 13.This is usually accomplished in a separate rim rolling operation.

As best shown in FIGS. 2 and 3, the container side wall 13 has formedtherein adjacent the open end of the container 11 a lid sealing grooveindicated at 16. The groove'16 is provided by forming an outwardlyextending annular shoulder 17 in the container wall 13, which isconnected to an upwardly extending ring 18 which, in turn, joins with aninwardly extending annular shoulder 19. Sealing groove 16 is defined bylower shoulder 17 and upper shoulder 19. Tapering upwardly and outwardlyfrom shoulder -19.toward the mouth of container 11 is an annular wallregion 20 which provides a camlike inner surface 21 at the mouth of thecontainer 11 which facilitates application of lid 12 as is hereinafterdescribed.

In accordance with this invention cam surface 21 of tapering wall region20 is provided with vent means in the form of a plurality of spacedrecesses 22 which are formed by outwardly offsetting sections of region20 (see FIG. 4). Recesses 22 preferably commence at the upper edge 23 oftapering wall region 20 and extend down to upper shoulder 19, butterminate at a point, indicated at 24, which is above groove 16 so thatthe recesses 22 do not encroach upon sealing groove 16.

The purpose of recesses 22 in the tapering region 20 of the containerwall 13 is to allow air to escape from the interior of container 11 as alid 12 is applied thereto.

It will be noted that lid 12 is formed of a single sheet of flexibleplastic material, such as polystyrene, and may be pressure formed in amanner similar to the container so as to possess a circular closuredisc, or face, 26 and an outwardly projecting annular sealing bead 27 atthe periphery of the disc. The lid 12 is formed :above the sealing bead27 with an inwardly and upwardly projecting ring portion 28 whichprovides clearance for the sealing bead 27 to snap beneath the uppershoulder 19 in container wall 13. Lid 12 may also include, if desired,an upwardly extending annular ring 29 having a depending skirt 30thereon for covering container rim 15 when the lid is in place on thecontainer.

FIG. 2 illustrates the manner in which lid 12 first engages container 11as the lid is placed on the container. Suitable equipment, not shown, isemployed in most pac aaeaeoa ing operations for conveying the lid to thecontainer and for thereafter rapidly forcing the lid into and on thecontainer. It will be noted that the inside diameter of wall region 20at its upper edge is greater than the outside diameter of lid bead 27and at its lower edge is substantially less than the outside diameter ofbead 27. As the lid is forced down on the container, sea-ling bead 27contacts the cam-like surface 21 on the tapering region 20 of containerwall 13. Inherent flexibility of the lid 12 and flexibility of thecontainer wall 13 permit sealing head 27 to be forced down over shoulder19 of the container without any permanent distortion of either the lid'or the container. On clearing shoulder 19 the lid head 27 snaps intogroove 16 and wedges tightly therein forming a dual seal with the lowershoulder 17 and the upper shoulder 19 of the container wall, as shown inFIG. 3, thereby assuring positive closure of the container andprecluding accidental discharge of the contents of the container.

From the point at which lid head 27 contacts sloping surface 21 ofcontainer 11 there is a tendency for the air which is trapped beneathlid 12 to be compressed Within the interior of container 11. However, inaccordance with this invention, this entrapped air is permitted toescape through venting recesses 22 during downward travel of the lidtoward its seated position. Once the lid head 27 has been forced downpast the lower edge 24 of venting recesses 22 no further venting cantake place. Although further downward movement of the lid may compress asmall quantity of air trapped in the container 11, there will not besuflicient :air trapped to cause deleterious pressures to be built upwithin the closed container. More importantly, terminating the ventingrecesses 22 short of seating groove 16 insures that the recesses 22 inno way interfere with sealing engagement of lid bead 27 with containershoulder 19 and a positive and effective seal can thereafter bemaintained between the lid 12 and the container wall 13.

From the foregoing it should be apparent that this invention provides asimple, yet eflfective, means for venting air from a container as a lidis applied thereto. It is of significance to note that in accordancewith this invention recesses 22 can be effective to provide thenecessary venting action even though the recesses are relativelyshallow. Thus, in a typical plastic container in which the wallthickness may range from .015 inch to .025 inch recesses 22 may have amaximum depth of the order of 0.10 inch, less than the thickness of thecontainer wall in the region in which they are formed (see FIG. 4).Moreover, recesses 22 are easily formed and require only minormodifications in the mold cavity in which the container is formed.Tapering region 20 of the container wall would normally be formed by aring-like member protruding into the container forming cavity. Provisionfor recesses 22 can be made by milling shallow, spaced indentations inthe mold ring. No additions to the mold are required.

What is claimed is:

1. A thin wall, one piece sheet plastic container having an opening atone end thereof, the Wall of said container having upper and lowercontinuous annular shoulders formed therein adjacent the open end of thecontainer and providing an annular groove therebetween, said groovebeing adapted for receiving the sealing bead of a flexible lid insealing relationship with the container wall, said container wall havingan outwardly tapering region extending from said upper shoulder towardthe open end of the container, said wall region tapering to a diametergreater than the outside diameter of the sealing head on the lid whichthe container is :adapted to receive, said Wall region having vent meansformed therein and terminating at the junction of said wall region andsaid upper shoulder, said vent means being effective to permit air toescape from the interior of the container as :a lid is being applied tothe container, but only while the sealing head on the lid is in contactwith said tapering Wall region, said container providing a reliable lidseal upon insertion of the sealing bead of a flexible lid within saidgroove due to pressure applied from substantially diametrically opposeddirections to said head about the entire periphery of said lid by saidupper and lower continuous annular shoulders.

2. A container as set forth in claim 1 in which said vent meanscomprises a plurality of circumferentially spaced, outwardly offsetsections in said container Wall.

3. A container as set forth in claim 2 in which said offset sections inthe container are displaced from adjacent sections of the container wallby an amount less than the thickness of the Wall sections.

4. The combination of a thin wall, one piece sheet plastic containerhaving an opening at one end thereof, and a flexible one piece snap-inlid for said container, the wall of said container having upper andlower continuous annular shoulders formed therein adjacent the open endof the container and providing an annular groove therebetween, said lidhaving an annular sealing bead adapted to be received in said containergroove between said shoulders, the outside diameter of said head beinggreater than the inside diameter of said shoulders in the container,said container wall having an outwardly tapering region extending fromsaid upper shoulder toward the open end of the container, said wallregion tapering to a diameter greater than the outside diameter of thesealing head on said lid, said tapering wall region having vent meansformed therein and terminating at the junction of said wall region andsaid upper shoulder, said vent means being effective to permit air toescape from the interior of the container as said lid is being appliedto the container but only while the sealing bead on the lid is incontact with said tapering wall region, said container providing areliable lid seal upon the insertion of said sealing bead within saidgroove due to pressure applied from substantially diametrically opposeddirections to said head about the entire periphery of said lid by saidupper and lower continuous annular shoulders.

5. The combination container and lid as set forth in claim 4 in whichsaid vent means comprises a plurality of circumferentially spaced,outwardly oifset sections in said container Wall.

6. The combination as set forth in claim 5 in which said offset sectionsin the container are displaced from adjacent sections of the containerwall by an amount less than the thickness of the wall section.

References Cited by the Examiner UNITED STATES PATENTS 3,061,139 10/1962Edwards 22044 3,173,571 3/1965 Cserny et al. 22060 THERON E. CONDON,Primary Examiner. J. B. MARBERT, Assistant Examiner.

1. A THIN WALL, ONE PIECE SHEET PLASTIC CONTAINER HAVING AN OPENING ATONE END THEREOF, THE WALL OF SAID CONTAINER HAVING UPPER AND LOWERCONTINUOUS ANNULAR SHOULDERS FORMED THEREIN ADJACENT THE OPEN END OF THECONTAINER AND PROVIDING AN ANNULAR GROOVE THEREBETWEEN, SAID GROOVEBEING ADAPTED FOR RECEIVING THE SEALING BEAD OF A FLEXIBLE LID INSEALING RELATIONSHIP WITH THE CONTAINER WALL, SAID CONTAINER WALL HAVINGAN OUTWARDLY TAPERING REGION EXTENDING FROM SAID UPPER SHOULDER TOWARDTHE OPEN END OF THE CONTAINER, SAID WALL REGION TAPERING TO A DIAMETERGREATER THAN THE OUTSIDE DIAMETER OF THE SEALING BEAD ON THE LID WHICHTHE CONTAINER IS ADAPTED TO RECEIVE, SAID WALL REGION HAVING VENT MEANSFORMED THEREIN AND TERMINATING